Soil & Water Management & Conservation

Ii’r-’u.

Addition of Cover Crops Enhances No-Till Potentialfor Improving Soil Physical Properties

Humberto BIancoCanqui4

lDep 4 .AgronomyAgalcuhural Ressa.rch Ctnler_Hay:s1232 240th AcmHays, Kansas 676014228

Maysoon M. MikhatJSrJm 94

Sknr!hern t’ans Area-555 laSs 5551. CUAkron, CO 407550

DeMo R1 Presley’.Hop. of AgronomyKansAs State UniversityManhattan, KS 66808

Mark Si. ClaassenKansas Slate Univerclty202 S. RnuppHesston. KS h7OeZ

5 /

1 1

ii

C e r r ai re •ng lncr nrA attention tn 6 a ihditc nh inrrthe rnultitunerinn ihfl t ropping cx C mc p an Ut is in no nil irm in

ails, 60 mon ot no i an n mitrn ii 1 1 1 1 r

n ol 1 an i t nt C is i rlnred n. tit, sL an ay [ . b fl anti f dhns

in Zhn I x9, er on md \\ stIali 00-i ar residue .riflos ml tnt

if tarn ,nrc Kane- U 0)09 t3 Inst ( A prnscir idd’rtonal hnn1as inp5 It it 14’ 1- ljv’is-;. I’

Is

SSSAI: Volume 73: :Nnniher 4 • jolt—August 2Q11 N71

n tr is nr t n u. 1 Iii.. °91. On a nit lam anl Is’ am. rye -.snnr5’ 70 i, lo{\’,and ‘ms.on clover ivsbum ;n rvzafnm C: !- luced ,s mdin cased the urated Cdrauhc nducris itv A’ and n awnho1din capacity ahcr I or ot manags cnt (Ke.islingct a1, 1994),On a silt loam, rye and HV in notil1 rn—soybean rotations irocreased il tWry total porosity, and plant—available

while it reduced Pfi and penetration re.stance,aithoughK seas urnsff tel con pared with plots without CCs abet 4 rof 1.enserlt (S illarni! cit xi,, 200K,

Ohrr iiches base bound little or no cttcctS st ‘‘n sod

is’, ‘teal pnp’’c’ 0 n a sandy loam, Fl’s and cc nucir ;vhtt ii

5 9 1 I I

and Cc nrun i ‘-dit) 1 sIn loam, rye

oat in no-ril-.1 soybean did not affect p0 and had mixed impactson water infiltration and soil water contest during a 3--yr study(Kaspar et ad 2001). On a sandy loam, rye, FIV and ei’imson e.lo—vet under conventional rillage did not afflict MWI)A a.fter ofmanadement (Sainlu etal,, 2003), Similarly, on a loam, red fescue(&tuOz i’rsbrg Li, bird’s-foot trefflil Lotus ornicu1atus Li, andsIb It’s id’L’suieao s,uias Li-in no-ru, after 2 yr of man,spemcnz,had no effects on soil hydraulic conductivity drhoueh macrovornstv was tmprovcd Carof cit xi., iOtF

‘, After 3 yr. crunsonI r “ C’ 5d c t i, e,,,s e ib t a oils

loam under conventional tillage but had no c’ffects on a clayloam (MeVily as K, 1989’;, The same study showe.d that CV in.—creased water infiltration irs both soils, In a 2xyr study, Is-lubiruand Coyne (2009) found no diffdrences in 0b among four CCsincluding mueuna [s%-fucunapruriens(L( DC. car, utilis (Wall, cxWight) Baker cx l3urekl, Doliehas lablab ([,rblab vu!o’ Savi,cv. Rongail, canavalia (imsra/,,-z -nsiform, L.- DC, j, and cr0—tala na— (O—,otajbria pan/inn Schrank when tilanted into fallow ndepraded sandy Jay. sandy loam, and loamy sand.

Ibis literature revIew indicates that the impact of (Pus ons(P.l physical properties can he variable - C over crop impacts madepc.nd on the type of CC, type of soil, tillage an.d cropping sys—tens, management history, a.nd climate, The literature also mdi—cases that most of the previous studies on CCs in relation to soilphysical properties were siort term (<5 r Further assessment

I I sponsc 0 1 l: s on 4c b V term ap r rs

, jsrsnind risc- mp acts of C-Cs. Svcc.ticailv, the csstc-nt too-k d-,- ,,-i,,,’,,,--SSt-i

-, -J 1 ‘Sn,

Martins or sl,, TOOK -

‘1 he additional nput od abcsye— soil hc-iowground biomassfron-s CCs c-an increase rhe SOC corice nrrrtion (Ke.isling cit xl,,1994: Dahney et al,, 2001: Reckly ca al,, 2003: Sainju er a.,, 200:3tVii.iansil rt ai,, 2006; Martins etal.,, 2009i. This increase in SOCcs.srtcc titration nsas’ imp rove soil physical properties. Some stud-is’s have indicated. huwcvcr, tisat (PC say nor always snercase

SOC c’’nccnrratiors Mcndes cit il., 1999 Fmo,sntnc cit .l - TOPS:

\f,bron Lovne. 1009 -- ‘Fhe info rose -‘f CCs on ioil phvcscai’

ecnrrsrion, Studies ,tssessing rIse relanonshps between ‘oil hvsi—cxl properties and sOC cutsccnrration under c_ru_p rotssnoIs base

bound mixed results. It rIse central t. re it Plasns. SenlatsIn cit 0.

1005’ found that an Increase in s()( - vt1s diverse crisp rotatonssc-as poorly corselated with soil physical properties .Sinsilar studsics assessing the mai’tnitude of the Cd tesce ofCC—i,sduccid SOCincrease on soil phys-ical properties are needed, ‘Th.us, the objectiveo-f this s-tud. was to quantify 15—yr cumulative impacts of no-tillCCs on s-oil physical properties and to study’ the relaticsns-hipshe-tween CC—induced sib ant.es in SOC c.o nc.entrati-on a.nd thephy’ical properties ufan rgiustoi’i n south -central Kansas. disc

ft sit “0, ,.1 ‘ 1

on s,stl vi sicaliisdhvdrstolic pror-ertic’s. sod ii - the (P -

— t.u ‘s

- cc’ ii

ated with changes in soil plsysieal a.nd hydraulic prspertics.

MATERIALS AND METHODSTlsis stud.y- scat conducted on a long-term experinsent of CCs. at

F-lesscor KS, tlsat was established its 1993. The experiment ss-as csn a

(ls-a.r vOlt loans (a hoe-silty, mixed, supemacris-r, mode lidicArtiostoll’iisIs ,s -‘0li’c Sofa. this sod is sleeP o,l n,,’deosreiv si-ri divined. is ills

no,, otranotk 115C mean ann uai pres piraticn tom the ss1s rrgion

cr151 an rite m,cart ant,.uiu tentperatos is

1 bc-c speriment 5555 , randomni,iesl ,socn’lerr dcsign consist—

sg of 12 treatments in quadruplicate n-csoiting hem a.fiictoniai cocnbi—

nation of tlsree treatinicots of CCs and fi,ur N rates, It thus- isad a total

of4$ plots, each 6 by 13.5 m, The treatmetsrs were evaluated in a winter

wheat—grain sorghum rotation, In all years wheat was no—till planted

into grain sorghum ttuhblr in the fail and h,irvested in June of he next

year The CC treatments acre imposed ffrr wheat, and grain sorghum“as pl.mttd n June ut the thllowng cam

The (iC treatments -sect changed doting the course’ of this lung-tern saperimenc, Is shot t in IShle I - Hairs ‘-‘etch scas used is s-inter

(ix OctslCs’t’, I so,! 1000, ss—bOe tis,, mmmcm CCe SH md hetS

is-crc used between 10-02. sod 2(108. Llecwccn 095 and 1900-ion-CC

roca.ooo was ccsmpared ss-irh rwes rotations in wh.ieh HV was piai-itcd itsthe fail a-nd terminated either early (MayOr late (June) using reduced

rillage (TitbIe 1). Between 1997 and 2000. the no—CC rcsrarion was

compared with two rotatsons in svlsich. 07 seas remn,itsarecl etiscr byredoced ciliate c,r by herbicide (no—dPi’.

so, sfPi sates 555.5 dsc is- sasoe1,and iOns it-se, iceamniscnr Sonsis

sc-crc secomplished cc hoar oh-anging. thc oomher c’ftrearmov-oi-s, dots,

csr rem iearions, The summer CCs sc’ere p-Lanced sLss-srriy aker wheat h,ar—vest in slImmer and eernsinamecl- its September or Oceohee That-c lots, ascc’t II as’dse no—CC rrearm,—nr, were nsanaged under oct—till. 7hcat onderno-Oil was crown without ferrili-cer across all plots in the transicion

lstrwtc’n 10(10 and Is 1

[he 117 seas ‘ceded so imlisl-’i’emosi’cm 0’ ears ‘-‘-a-- 01

1472 SSSAJ: Volume 75: Number 4 July—August 2011

Table I Description oi the management ot three cover crop treatments at Hesston, KS.‘ear Cover crop treatment Seedhed preparation Seeding rate Termination date Termination method

.rrsfiuoremethyi2-pvrsd.invl)oxv]phenosv)propanoate]. inno’tilI

HV plots, glyph.osa.te [aV’((phosphonosneehyl)glycine} alone or with

2,44) [(2,4dichlorophenoxy) acetic acidi or dicamba (3,6.dichloro’

2-sncrhoxybe.n.zoic acid) or bot.h were uscd to control COT and weedstatwccn crops. For risc sonitnet CC s, [515 and Si-I were plarstr.d in rows

at ant aos terminated us the hip a tha crop- roller hsilowcd s

Pert cida aptiicanos:. Psc N1I nO [MS -‘crc last noun in the summer

is ss wig

“Ira-n, sssrgitjnu s’s planted so the corresponding car’ at a rotc of103,780 seeds ha at °6-cns row spacing. Plots received I S( kg P haas triple superphosphate (0—46—0 N—PC))_K2O)a.t sorghum planting.

Nitrogen was broadcast before planting) 1996—2000) as ammonium oP

trate (34— 0-0 N-P205-K20)or injected. 46cr planting (2003-2.009)

as ureanimmonium nitrate (28—0—0 N—PO5—K,O) at 25 cm fromthe row n the corresponding piots at the sates specified abor. Arrazine

.h-hloni--,V-crhvl--V- - I -rsirthvlcthv[ -1 .[S’rnane-1-t-dsamsnc’ plus

rersiachlor 2—chiro-,V-cthl4w s thvlphevl.i-:V’tl-nscrhuxe. 1-

mrths-lethd)acctamsdt - tirocided na-i-met pence weed control m ununssrrgisusso t5’Pcr sirs t;a0tesI- st a eaten I P0 [ ia_i at 20_cm: rose

:s. Plots receis-’cd 1 7 I-g l-° ha at wheat planting, and N was- broacO

cart before planting- as ammonium nitrate (34—0--0 N—P,05---K50)inall years except 2008, when urea (46—0—i) N—P205—K50)was utilized,

in this c-C experiment, CC aboveground residues were not bayed or removed Cr othfitrm stars. F-or this study, data on CC tes-iduc petaduced

Cr risc last three C C rotation c-ycles (210---i, 1006, and 2008) were ana

ste 20 i 0 its saosarra;fis:ked era-ass, Pcsscrrarsoss rcsis-tasscc as :srcaoa red,

55 sespiscate. within rise satsse. plot, Cr tIac ii-- to 4 4— to 8—, 8-- so I 2-—, and

2- to 20-cm. soil depths b-y a s-tatic hand cone penctrome-tcr (towcry

a-nd Morrison, 2002). The diameter of the cone base was-- 2 cm and theangle was 300. Malutnr-rric water content was determined Os-r risc samesoil depths as- Cr penc-tration tes-istanec sasing time domain s-rIle crome

Field Scsssat 1 DR O-4i ‘sin mnsor’ree octet, Spectrum Err hsrenl-ogirs-,

— ‘i —

a - csr’ecned, sears sj5ot5. set-s corteprte0 ss :sh sittrtcsrcsts tsr ‘‘si scare a

Colt-nasa i, iroatroents 2 assd -i.

adjusted to elitninate their dependence on s-oil water content, Sevens’approaches were s-t-udied (Yasin etal,, 1993), but the ratio ofcxponentialfunctions: proposed by Busscher et al, (1997) and Bus-sr-:lscr and Batier(101)3) fit our data Cr all treatments. 46cr adjustment, Cr- correlationIsrtsvectj penetration resistance .-and soil ss’.iter content var not signifi,-aiar Foe v0,stsSpie, iseCse .rdiuscoses a. pcntnratior csitance was cot-

4 i)7’1, 1’ -s 101)- witls wates content, One afire

jot correlated 01)2, P silt5’ ts’r the 0- es-i-ens-depth.jteannent etleets are thu Ji.scussed based ors the adjusted data. Details

ott the procedure for the adjustment of the petsetration resistance datawere given by Blancss-Canqui et al, (2.006). It is important to recognize

titc difficulty, however, in correcting the dependence of penetration resistance on soil water content because, at this point, no univrrsal corrective equation or model exists (Yasin rr al.. 1993; Busscher er al,, 1997;Busseher and Batter, 2003).

Sod tesuperature was measured using a dsgital thermometer in

riplivate withrn ea, h trrarmcnt plot at i-, 8-, 1 2-, and 20-cm depths be

ts-en 1 100 and I 00 h. \X-’itter infiitratsssn seas measured sirs sag double—5 ttr,srjnetets ,srrjer cons serene he-id Cr 3 Ia Tee-odds etai . 1002

The dianseree of t-he issuer ring was 15 cot, svhile the diameter saf the

outer rirsgwas 27 rtss. Farthwormscs- t-srai s-red in 0.2- byOC-nr seth blocksrscavared -with a spade were carefsrlly hand sorted send counted in eac.hplot, Infiltration measurements assd earthworm. eo-ursrs -avete made ernlyfssr plots receivin.g lii..) .l-g 2. ha becastre this nate of N applicatioss isrehal liar the svhe-ssr--ssrrghurn rotatissss-s irs the region.

t:’sses. sehule the is-st-oct. -:,...,,):: cssees- wes-e sss.erl rise rIse cletermiss,atis:sas sot

sos il ssaecr retention, ,sssd C. Btrlk sampies were ai-r dtied, get-s nv crtrshed,s-ott) ps--sr--ed ehmotrgh 2-, 475.-, arsd 8-tons sieves, A fraction ssf ea_Is. bulkr-s-,iI s-’-tnple. was ettrshed, ground, and passed tht-arrgh a 250-itm sieveeta determine the SOC concenteac ion b-’ the d.ry cotnhr.tstiors siseehodPOison and Somtnmrs, 1996), \Viat aggregate stability rests determined

l’s rism .iet-uessssg rseC,sd Cr the to S-tons tsr Ore s ggregsrtcs‘5:55:5055 anot -tntrsr:s. O’Oc, Isle .sn’rsotm ot ‘-ott v’5tt.ast5t4 socses

setI’ 47’S- 1-- -.9 5- -rod t) IS-resna .5555005515 .5.55 ssss:j5 st-test ,s:sst ascii

Cs srattiy :ess:l-:a-s-:od JC55Os’

i-ta. icy sole-h ti’rrsss sat0 .d ‘sale-- rs:sduced tillarie997 1998 1 - no c-over ert-;rp eer.luced 01108-c

2. hairy v-etc-h iermin-,ried by tilliage reduced tillage1. hairy vetr::h lee ml n-sated lay.’ herbicide rs.-duced tillage

‘9’r0---2(X10 I tsr c-over ceon neduceal )iliarlles’saire-v-etrrh rsnrrnr-ss,a-;s:’sl Its tiliage s-•st s—till

i:sot-s,lizsssar) r)esttrssr,sP: :5-s isse ‘ rgi’sssrts 0.-OS-S. Ire 5,5155555 tsr Psi; is’sli, ;sj its (rsissssss-s . toss Iteat Os(’nst

ns:sd.sr.s-s-e ;i’isps-s-a

redtrceri 15II,l1S55

22- sOny

22 May

SSSAJ: Volume 75: Number 4 July—Auttust 2011 1473

M\Vl)A. -gates bet’ 125 and S urn in dramerer -s-crc Jarsi

as nsa nsaggrrgares ar.id those ri). runs dia nsrmwe.tr alassrfied

.as sn:ctoa rcgatesr Tisdali and Oades. I 9ii2).

The Pro .tor o at difittent levels ef sod water content was detemined by the Proctor test to assess- s.oil aasmpactibilitr lAmerican Society

mesh nate missed ‘amt:r water. rutted to the srss.ndard. Prose rot

ung the Proctor drcsi, hasntnen The atrt.ou.nt of water added ts.s the sd

.s.aniDles in each ease varied from air d.ry to near separation, The cowepact.ed. soil in the Proctor mold was trimmed, weighed, and. a subsamplemyers drseat to irrrrsnsnc risc gravsm-err:a warcrcrsnrrmst, which was med

:)vrrse Prestos mnoi.d- ccsh trw: Isp Mg tsr lhe Prs.sa:o r p was alma ttedagasnst the tr rne.trrcwa.ter content to obtain the compaction curves

for ea.eh individual sample. A third-order polynomial curse was fitted tor.hss data &srderrrrniss.ing h-orb the Proctor osaximum ofthe soil uample

aru.r aurstem. he 01 she poivnonsmai curve mu as selected as the

pros russ mass-morn Cc Pro:or restss,u usuter sntcrst us ri-ac Soul spited

corstent at which the Proctor reaches ansaxinsum value or the Proctor

maxinr.urn p. The Proctor rests were peri-drmed only for plots receiving 0and 66 kg N hsa 1 Proctor snaaimum is5, wil.l be referred to as maximum

and Pro .tor cs-irical 5-5,Sc C. sSr C.r Spacer- seleCt

fEe K us asdrrerrrsrued our the in tact tori cores br the ciunstans--head

i R ru Id ,ui 1 2 r \‘, ng A 1Ctt ml i ii II “ ii err

were reeaturared thr 24 Ii, weighed, drained Sequentially at marric potendais ofO, 99,5, ---1, 99,99, --10, -‘00, 9900, and --‘1900 kPa by pressureextractors, and the volumetric water content determined at each pressure

head ([)ane and 1-Iopmans, 2002), After seater retention measurements,

seas dererm;ssed by the sore nsedse’d C rousman :nd Rcinsch, 2t.5)2.

It us sprint tarst to restate that, Ira slurs rxiserrrrsrnr. H V w5s the CC

crop am uses duane, sue trrs-r 5 55 uwc-,5- iru- a titer N i—-i or I - MSduring the last 6 yr of the. cxt.rerisnent, Thrrs, iris possible rh-st chrusges insoil properties observed at the end of the I 5 yr sPay not he solely due tothe- cover eroppi rig of Si--I artsl LMS but rather to the cumulative effect

IV plus r ithrr SN mar I 915 because IV se5s. erowrs its the same plots

tsr Ire snuaimai. Wheat was urs.awn acrs.srs all plsars .rmt ‘he rrans-iniom-s v-earbetween 2000 assd 2002, ys-hich put-ssiblr.- reduced any residual effect of

on s-oil prrspert.ies. Furrhernsore. bssr:red on other s-tusSles, I-IV strayIfsmlssrmsnso its al.. 1992: her sling et .rsf, 1994: Villaem-mr Ir-t al., 20 (6 -or

Data AnalysisDifferences irs saai.l properties and rcsid.ue amount among the CC

trearrnrtnts a.nd tIre. N application rates were tested using PROC MIXEDmum hAS (SAS it sri-sure, 20 I I i. For ehc amsaivsis mm-f the data ran pesurts-a

soa. :ma.srmuru’

, -as stir a ssatrr sonmrersr K.,s-sm I ss—arer re-sr mrs nuts, and 9CC nones-sm-sr <-mrs-s us. the ((sr-si hsctorsssemr

tre,ntunarrs. N amiieatms’n level. amasS 5usd slv-ptIs. us is It the rand run rluessrrsWere rcpiscate arid its irrseractiuarus se-irh CC treatment send N ssppiicssplop level, For the analy-sis- of the data on cumulative sv-smntec inliltration,.c’artfwortn population. and CC tem—idue amount, the fised. factor was CCtreatment scud the randorsr Deter was replicate. Sirarss amon rreatsnenrsWere asurrm-y.rred assssg 1591 hANS us PROC SllXEf9 Betirre he muse of

PROC MIXED, the ssles-rrd ulat,s mess-c trstc,! Sure mmorssm,s!-stv susung rise

S-isar’rrss —A 1k tern srm.,r th trsc 1:, ‘hr ut-ed: ti-mrs rime data ssrremmuurufssei:

ulisteibureef eacept the K, data (SAS lns-tirure, 2(111, The m s’alsseswere iogaritlsnsir-sa,lly transft,-rsrred to normalize the data, The PROC

CORR peoeedure in hAS seas used so s-rudy corr-t-iatiorsa anssursg the soil

imrmapetries. Cosrrlah:orru berwc-rru sne oml p-b,s s.]. ‘teeters’s and SOC

lusdependu-ust ctfects su she CCaon sIre soil plsvsucai properti’a-s with-outany possible confdundimsg

- effects- o-f N applicariors , Statistical differenceswere ompunted at rh-c 0.05 pmbssbiliry level unless otherwise irsdieated,

RESU [‘ESSoil Compaction Properties and TheirRdationships with Organic Carbon

Cover crops and N rates had no c’ffeet on penetration rcsis—tance hut affected other soil compaction properties. Cover crops< N rs-te interaction was riot significant (Jr arty soil property.Mean penetration resrsrancc acrcussN triter ursa 0.88 :9 0.19 SiPsmean a- SD tSar SH, 0.89 an 134 MPa for EMS, md 0.91 j

09)8 MPa for plots sv ihout CCs at the 0- to ‘25-cm depth. C,overcrops ffcted in the 0-to 7,5-cm depth, hut N rates had no cCfeet, Swan hemp (1.23 ± 005 Mg m’0) reduced 0b by ,ihout 4%,but EMS 1:1,24 + 0,07 Mg m3) had no effect relative to plotswithout CCs (1.27 + 0.06 Mg tri Differences in 0h betweenSF-I and l,A1S were not sigmhcanr.

lioth CCs and N tates had sngnifieant effects on Proctor iN.nlssxrsnrrm h’

up55u risrcal a-ater content at C0- tur ‘n--ann depthbut not at the 7.5-’ run I 5’cns depth (Fig, I and 2), Cover cropsinfluenced Proctor p1 at 0 kg N ha 1 (Fig. IA) hut had no effalctsit 66kg N h’0 at any depth (Fig. IC and ID). Figune I A shows

va_bess of Preucresr 9 deli-mv- the’ srlIti:al scarer s’ranrcr-st rrrsdc:rscare -501-. srawer rh 155 rs. pIts vsuthurar PiCa. For

sat m’sc’ar ssutsrsat-On, Prs..ret.sar A 5,serween p1<s sv’irh andsvithout CC:s did raor suffer: Ar ml) <sag ].‘4 ha . ssraximurrs 5-<9 underS-Fl acrid LMS was alausaut 5% lower than ins plots without CCs(Fi’g. 2A), Similarly, the crirical water content in plo-ta without

was I 2% lower s’han undc’r SD arid 9m.m4s5 lower rh,ars under

5 S 5 ,,,,, a 5-,

rriflcarit.Nitrofien application rcds,sced tIre rssaacimuos 1-5b from1.65 Mg- na99 at 0 kg N haxi to-- 1.62 Mg m at 6-6 kg N haxi,hut it had so effect on the critical water content.

Sod nusrinpuseten pararne trw were . rrrrelted su’rth efmarieemss SOC s.’ srecnsrratrnn. Corer dips ansi ,\ rates ,sfttnred SOCau’Ptc’isrtdtlr nI at the 0 rus “.5 -ens depth. ‘sut the CC ‘a % tare ri’

‘.f5tSCtiOt5 sr<a.s t5Ot Sie,55SPes5Pt, Avcrrsged sscto.sr, N rates-s. t.:,’ae .4CC

1474 SSSAJ: Volume Ms Number 4 iuly-’August 2011

3.3

CoO Watsr (otsot (kg kg)

MO OtS 0.10 3L25

000 (LOS 030 (L15 02O• 025

CoO Water Content (kg kg4)

Fig. 1. Mean Proctor bulk density at (A and B) 0 kg N ha and (C and D) 66 kg N ha for three cover crop treatments at two soil depths. Errorbars are LSD values to indicate significant differences among the cover crop treatments, Differences among the three cover crop treatments in Hto D were not significant.

1.04

102

Fig. 2. Mean Proctor maximum bulk density and Proctor critical water content at (A and 8) 0kg N ha and (C and D) 66 kg N ha under threecos er crop treatments at tWo tOil depihs Ban with difbrent Imsercase letters within the same sod depth indicate sii&ani differercee; nsmdoc.ates no s(gniflcant difference, among th(:3 three cover crop treatmeott withi:n (he same depth.

0- in 75-em tOt drpih 7-to lftnn tOt th’pth

0KgNhw A

s Late-Maoo.rtng SOtiean

Li

Soon Hemp

Ii

1.3

((JO 00$ ((.10 (LIS 010 0.25 0.00 ((OS

SIt Kg N hr3 C

(I- to 7.5-em teSt depth

1.4

S6KgNhn

75. in 14 con toO (thplti

t.74

172

, 1.70=

16$

1.66

S

162

oer(rnp 1.a--5isim-hhcan

Sn tk’np tn toner Crop t.to1isring

a372

(.70

3.5$a

St

aaa

I

5nnn ttrmp

So (wer (;rop Late.M.sttertng No Cover C rup t.roe.Mstur4n Senn HempSoxtwse

SSSAJ: Volume 75: Number 4 • July-August 2011 1475

coer L5’htrurffig “unn Hemp 0 3J o3;rApt4rn Ristek isa’)

Fig, 3. Mean soil organic C concentrahon under (4) three cover crop treatments and (8- four N application rates at two soil depths. Means withdifferent lowercase Jeiter within the same soil depth indicate significant differences; ns indicates no significant differences among treatmentswithin the same depth.

entration was l3 tones urearer under SH and 1.2 times

greater under l$tb than n Nuts without OCs or the IT tocm depth :Fig: 3A. Ar the same depth, averaged across CCinents, the SOc. ucentration increased svsrcrnaticaiiv with an in

crease in the N application rate Jig. 3B). The SOC concentration

increased by 13 times, from 0 to 100 kg N ha Fig. 38) thgure—sA shows that penetration resistance was negatively correlated

——0,51) with SOC concentration at the 0kg N ha application

Ill

0 5 10 IS

Soil()riinic Carbon tg kg’)

rare at tI-ic 0,09 probability level, si’ggioring that an increase usSOC anneentrarion ma reduce soil compaction. Across the thurN levels, however. penetration redstanee was not eQ rrelated withSOC concentration (Fig. 4W, While o was not correlated withSOC concentration at 0 kg N na ‘ l’lg ac.;. it was signihcantlvcorrelated across the four N levels Jig. al3. decrcas,n with anincrease in SOC concentration.

20 0 5 10 15 20

Soil Organic Carhon(i kgu)

Fiv,. 4. Retationship of coil organic C iSOCt concentration with ‘A and B) enetrtion resistance and (C and 13; hulk densitt .oe at (A and C)i s ‘a sod is ‘sq” ‘c an ,,vrot P is C (Os ‘0 40 k \ ‘a ‘r 59 a’ so

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SS5AJ Volume 73 Number 4 • Ink—August 2011

Soil compactibul.ity as determined by the Proctor test seas

more strongly usfiuenced than penetrati.on rc.sistance and Pg by theCCindueed increase in SOC con.centrasion regardless of N applicarion level. The maCmum p was negative.ly conv.lated with aCCduced. increase. i.reSOC conce trar.ion at 0 kg N ha (r =

—029; FIg. 5A) and across N levels (r = —027; Fig. SB). Similark;the critical water content was strongly and positively correlatedwith a CCPnduced i..ncrease in SOC concentration at 0 kg N ba(r 0,85; l.hg. SC) and across N levels (r 0,8.2; Fig. SD). Themaximum Ph decreased where.as th.e criti.ca.l water conren

creased linearly with an increase in SOC.. concentration,

Aggregate Stability and ts RelationshipswIth Org nic Carbon

Cover cropping improved soil aggregate stability (Table 2;Fig. 6), but N rates had no cf+2ct on agg egate stability. The C.Cx depth interaction was significant, indicating that the. CC 312cron aggregate stability depended on soil dcpth For the O to 7Ssemdepth, CCs. increased the amount of 8 to 4212mm aggregates

by 36 times, 2. to 4,712m.m aggregates by I ,8 times, and 0212 to0,12mm aggregates by 13 times over plots without CCs (Table 2).in cont.ras.t, the amount of <ft25m.m aggrq ares in plots withoutC.Cs was gas.ater b..y:. 12 times in the 0 to 7,12cm depth (Table 2).For the 7i. to I 12cm depth., LMS incrc.ased tile amount of 2 to4,712m.m aggregates by I, S times over the o.ther teeatments, Covercrops als.o i.ncreased the MWDA by about b I ,8 tOtes in the thto 212cm depth (Fig. 6A), For the 7,12 to I 12cm dep.th, LMS in.creased the MWDA by about by 12 times rela.tive to plots withoutCCs (Fi.g.. 6A, The increased aggregate stability with CCs agreeswith the fi.ndings by Villamil et xi, (2006) but contrasts with thoseof Mchily et al, (1989) and Sainju et xl, 2003, who reported nosignificant impacts of CCs on aggregate stability. iy aggregatest;.rhility was stro agly sas elated with c.han.gcs in the SOC conceretration, Ar 0 kg N haO, the MWDA. was positively correlated (r

021; Fig:. 6B) with SOC concentration in the C to 7,12c.m butnot in the 7,12 to 1 12c.m depth (data nor shown), Across the fourN levels, the IPIWDA. was also correlated (r . 0,40; Fig. 6C) withSOC concentratlon,

I 5

I A

0Kg N ha’

• ,‘,0

16 (• NoCoverCrop

2s Late’Matur1ng Soybean

o Soon Hemp

Maximum Pb = 4L013*SOC + l84r”0,62;P=fL01; n”12;

RMSE =O03

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eh %00

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0 5 10 15 20

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0k “00

CWC=O,003*SOC ±0,123 = 0,67; ss(14(1); on24;RMSE = 0007

D0,10 0,10

0 5 10 1 20 0 5 10 15 20Soil OrganIc Carbon (g kg’)

Soil OrganIc Carbon (g kg’)

Fig, 5, Relationship of soil organIc C (SOC) concentration with maximum bulk dens.it:y at (A) 0 kg N ha”1 and (B) a.cross four N applIcationrates and the relationship of SOC concentration with critical water content (CWC) at (C) 0 kg N ha”1 and (D) across four N application rates forthe O to 7,5em soil depth.

SSSAJ: Volume 75: Number 4 July—August 2011 1477

Table 2. Waterstable aggregates for each aggregate size fraction from 8 to <0.25 mm at two soil depths as influenced by covercrop treatment across four hwek of N

Water..stable aggregates

Trei0ment 3-4.75 mm 4752 mm 2—I mm 1—O.5 mm 03—0.25mm <0.25mm

-

Means I leaved by the cnne n:,ea .eft<i witn a es>Isnnn and

Hydraulic Properties and Their Relationshipswith Organic Carbon

.Sunn hemp increased water mhltranon rates and cumulative i.nfiitration by three times relative to no-CC plots (Fig.7A). The mean (± SD) stead a-state. water infiltration ratewas 4.8 ± 2.5 cm h for SH,3.s + 2.0 cm h for LMS.and 1.7+ L2 em h fdr no-CC plots. Diffi.rences iii ready-state infiltration rates and cumulative infiltration be tween the[MS and no-CC treatments were not, however, sittniheant.Comel re infiltration ‘s-as positively correlated 4 = 1)5±with SOC concentration it the P.07 probability level Emp. fli,

Steady-state inhitration rates were also correlated C 0.50) withsop; concentration at the 0.1 () probability level. The increase inwater infiltration with SH was related to earthworm population.[he number 0f earthworms, mostly

[um/n-imu retrestri, P., wassix times greater m SH plots than in plots without CC5 Fig. S.

[lie etleet of CCs on was not, however, suniticant,Mean geometric 1w SD tor the U- to “.5-cm soil depth was

1,58 3.43mm h flir plots without CCs, 1.05 ± 1.38 mmCr plots under LMS, and 1 .3S .:fz 1 mm h under SM Dataon K55 within the same treatrnc nt were highly variable. The coefficient of variation was 217% Cr plots with no CCs a.n.d 131%f4 those with CCs. Si.milarly, there was no significant im.pact ofCCs on soil water retention or plant-available water (data not

Water Content, Temperature, and CoverCrop Residues

Cover crops affected the held volumetric water content(Pig• 9A.) and soil temperature’ ( Fig. 9ff). Soil water conscut wasgreater u.nder CCs than in plots without CCs by an average of35% at the 0- to 20-cm depth. Soil temperature during th daywas also consistently lower under CD.s than in plots withoutCCe On the average. CCs rcdueed the sod temperature duringour held measurements in many spring by a°C at the 5-em depth.2°C at 15 em. and i”C lower at 30 cm, As expected, the volumetric water content was h ighk correlated with soil temperature)Fig. 9C). I)itfrenees in soil temperature explained about 62%of the variability in water content in the 0- to 15-em soil depth.

The amount ot residue produced between SH and LMS diPfeted significantly. flie CC vs. N rate interaction for residues wasnot significant. Averaged across the three previous rotation cyclesand N rates, SM returned more residues than Lb’IS. Sunn hempproduced 7.02 ± 2.2 Mg ha of residses while LMS produced5.32+ 2.4 Mg hat, indicating that SM re.turned about 32±more residues than LMS.

shown)-. Correlations of water retention, and p-iant-available water with SOC concentration were not significant.

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Fig, 6. Mean weight diameter of aggregates (MWDA) (A) under cuser rop treatments and it relationships ith soil organic C at (B) 0 kg N ha’’and (C) across four N application rates (0, 33, 66, and )f kg. N ha-” (or the 0- to 7,5.-cm soil depth, Bars with different lowercase letters withinthe same soil depth indica.te significant differences,

i:’c i 111

c I arhan :5 h-’ i

347)3 SSSAJ: Volume 75: Number 4 July—August 2011

311

ihe lower p. Prcctor p, and maximum p’ combined withthe Creasee criti.cai water content near the soil sssrfcendic.atnthat CCs reduced the nearsurface soil’s susceptibility to compaction. Although the application of N appeared to offset then hr e S S r .. w F

ncrcanng the crincal water c went at which the maximumoccurs Ftg. I i) the results suggest that th addition of (ZC5 touooill systems may bc a strategy to manage the riskt of excessive

soil compaction near the soil surface, While there were no dif

ferences in penetration resistance, the data on og and Proctor Phsuggest that CCs may reduce some risks of soil compaction. Thereduced soil compactibility onl- at and below the critical watercontent Fig. I A ndcarcs that the henehcial cct of CC. thr

reductng compaction ltminsh when the soil is near saturjt!on.

War(wdog (m’m°)

0.11) 0.11) 0.26 0,34 (1.42 050 12

SO) Temperuisre i’C)

14 16 18 20 22

Water Coutent (itt3 rn°)0 0,1 0,2 0.3 0,4 0,5 0,6 11,7 158

Fig. 9. Cover crop effects on (A) field volumetric water content, ill soil temperature, and (C) the rebtionship between field volumetric watercontent and soil temperature across four N applkation rates (0, 33, 66, and tOO kg N has’) and two soil depths. Error bars are LSD values tocompare cover crop treatment differences within the same soil depth. Data on fit.ld volumetric water content and soil temperature were collectedin late April 2010.

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5 tO 15 20 25Soil Organic Carhn (g kg°)

Fig. 7. Cover crop effects on A) cumulative water infiltration and (8) the relationship between cumulatise water infiltration and soil organic C.Sieans with different lowercase letters indicate significant differences.

DISCUSStON

it3o0

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Fig. 8. Cover crop effects on earthworm counts. %leans with differentlowercase letters indicate significant differences.

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residues on the soil oirface which is rvp.ical und.’r no-till condinuns. Duff srnces in residue ,ualitv may also have contributed

duf:erial impacts of SH and LMS on soil properties. 5mmhemp residues arc coarser and hcms icr than soybean rcsiducs andcan remain dccon cd Cr a creatcr icncth oftume on the soilsnrfdce. providing longer oil ,rtdcc protection Furthermore

rzemnsc experIment. C!aascn 2009. reported that SHr;-dues contamned ‘ kg of N while F MS residues had

I g kg of N soegesting that S i—I reodues mac deeornpoe atIosve r rate than L\-IS renduc due to loner N content

SUMMARY AND CONCIUSIONSThe additi.on of P P enhanced no-till performance b im

provin.g near-surtac.c soil piysicai and hydrau.l.i.c prop.crtic.s andinc.reasi.ng, the. SOC cenccntration in an Argiustoll in south—central Kansas. The hndings, in general, supported our hypothesi.s,which stated that Ches .s.igniflc.antiy impacted.. soi.l physical properties and their relationships wit.h SOC concentration. Across Nrates, C.s reduced b and increased wet aggregate stability andSOC concentration relative to plots withoc.it CCs. The effect ofthe as, h.o ver, cignilh ant primas..iiyin -.he 75-cmdcprh and only si.ightly in the 5 to I 5-cm depth. Cover cropsreduced the maximum i[ and increascd the critical water contentat 0 he N ha in the 0- to 5-cm depth, hut they dd northe Proctor parameters at bo kg N ha - fir the same soil depth.

Sunn hemp increased water infiltration and the earthwormpopulation. but dithrrrnces in these parameters between F-MSand no-CC plots were not significant The greater impacts of SHmay be attributed to the greater amount of residue produced by

SF-I than by IMS Both C(s inreased the soil water content andreduced the soil tcnlperatu re during springtime over pints without CCs, The application of N am 0, 53, 66, and 100 kg J ha -

had smaller effects on soil properties than CCs, An increase inthe N application rate, however, linearly increased the SOCconcentration, .A CC-induced increase in SOC concentrationreduced penetration resistance, p5, and .maaimum b’ while it

increased aggregate stability and cum.ulative water in.fltrationWhile the effect of CC.s on compaction param.eters, wet aggregate stability, and SOC. concentration was confined to th.e 0- to75-em depth, the SH-induccd increase in water infiltration .sugeests that the whole soil is a.Hhcted, depe.nding on the CC type.

Results flona this tucl sue,ge.st that CCs may rne.lioratcrisks ofescessive ncat-.uirf-,cc - compaction- and im.prcve

Sec

ccc ía ri a H mmcc re&.i --•- ris colT cii stil ccl by

mm S - r

the 2 con ccc r ration - _o-cr crops to has-c

snore bersefclal. impaerc °, ihysical properties at 0kg N ‘

risan at hid-icr N races or shc nm vcramtcd across the f.mr N cares.siigiestmng that N fern!izatmssn mO partly diminish the benefitstrom C(Js,

Jhe results from-n this wcs rk :mfi.er 1.5 s—r of C C nsaissgcmneuthave important implicatiorss Cr tlse long-term useofcuvc.r crimps][hey suggest th.at no -till farmin.g chou.ld be cc.mbirie.d or i.so.e

graied wit.h C’Cs to enhance the potential, of n-ca-till technologyfor improvir.g soil physical properties, i.ncreasin.g the earthwormpopulation, and enhancing SOC storage C-over crops nay bepsrticF-rh beneficial 6cr no -t5ll rotations with limited or no an—coal buomass uput or mIs suSteiuis where crop residues ,mre removedtot oil-farm uses More specific rrscarch ‘an the emsn trsbutsons c’t

CCs for offscrtsng the adverse eikcts of crop tcss.dne removal on

and the envIronment s 55 amransted, fienose sn regions with

OW precipitation -. StIll mm yr growisse (Cs mao reducenlarst-axaiiabie water Icr thm- masts crops, maoau’ement strategies.cccli as c-ark rerrnmnaton of CCc. that minImize reductionsplaist-availablc water should also be further researchc.d

R’EFERENCESAmerIcan Society for Testing as.I Materials- 2007 ASTM D698—07 Standard

test mnenh.oda Hr laboratory eompacricsn characi.eristics of s-oil usingstandard e.ffbre (12 4-00 li-lb/F-5 (600 (N-rn/rn)) ASTM 00. 5(2ccCorsho.ho ken, PA

‘lle.njamssin,jX%, MM Mikha, and MT Vigil 2008 Organic carbtsn etHers oncoil physical and hydraulic properties n a semiarid climate Soil Sd. SocAmJ 72 1357— 1362 002 1221 36/sssa1200T0339

Blanco-Canqui i-F, 111 La1, Lit. tIcs—rims, ‘MM Post, as.sd RiO lzaurralde. 2206.Curn-ssoveeimpacn or, ms--m.s-ssrflmcc so IpropmrrtiesoEncsiil[ccmrsm jim (I/sIlo.Soil SeP Soc Am j 70266—OS

I3lassco-Canqui, H, LR Stone, AISchlrgeL 50 Benjamin, Mi-c Vigil.:msd PAVI .Stahlmnum. 2010. C,stiou-cc arspeing .sysrcnm.s dccc ccci,,rHce osasmisism _onpvno in co-till coO,. Attn”. 102

iii1134..,gtniZOIi5.i 13ilIas,co (lam’,sissi, I-F, [R..Sto,,e. S I. Sci-Irgel Ui- Lot StE Vigil. H StAb,

arid PSX. Stah.linan. 3.mmm9 SIn-nil nOticed indmrasc its organic carbonmr,lucr, n,aximnum hulk de-ticits- of soils. Soil .5i. 5’- Au,. 3. ‘3 I sO —

1829. doi:I0.2136smailtmo8.0353iS,,mch.er, SM).. and P) ISaues. 2003. soil strength. cotton growth and inn yield

is mm sr,uthea’,ter,i USA cua’,tal l,’amv ,an Soil fill-age Re,. °-a is — I 59.dot ml 1016, .,t11.2m)03j)6.002

13tsscher \VL Pd. flauce CR. Camp. and R.E 5aika 1990 Correction f coneodes t2,r roll 15cr corsent dmrfrreno-s is a l.ovscmml Plain ,oil. Sn FllageRem,43205-’2F’. dn10.I0I6!Sm)It,7--l98i97)00015-9

( rot/I (2,5 deTourdomirirn, S. l//o,,uet, ‘rI 1—lailaire, andj Roger-Estrade.7007.Hydrau.lie cond.ucrivity aid porosity under convenniotmal mild. so-sillagrand the effect of rhrer .cmsrcics of cover crIsp in northe-rn France. Soil I_seManage 23-230—2 37 doi. 1.10111/) 14-75-274300073)008 Vr

Clause-n, (2(2 2009. Effects of late-nsaturing soybean and soon hemp suummemens-er crops and nitrogen rate in a iso-till se-heat/grain sorghum rotation. p44—4--9 In Field research 2009 Report of prtsgress 1017 ,Hailable at eeocksrelsuedu/library/crpsl2/crpi.Oi0pdf (seritied 23 Ape 20 li)’ Rat asState Univ A.gric hap Ibis. aid Coop Ext. S-crc. M’arihattass.

Dabney, S-H’-. 1998 th.oser e.--p iossacrsisn. setters-h-ed Eyd.rsslcsgy. j Siil ‘AhmcrCssns,.ry 537207—213.

I/)abise, Si-1, f.A Delgadnosnil i.’.i-352. Rccncs. 20(0. lisingwintereovsriso: rove soil and s-ant oaiimv. Cocoon. Soil Set Plant Ac) .‘12 1 22. 1 --

250. dc—i-. 10 1.’ (/5 1 ..(.‘/ (.1 - I 0-) 1. :/ m 11.0

— I,

cc del - 10.2 1 .Vs.-Ogrs i 9200001 1 9629059ii’04 (512ia

.-\igennmirat l’amp.,s. Soil Iliga Re,. Ss-IZi--1-Ib/.t,,,-IOitmls, SOItsIi O-c)f2-2t0s9- 1

0. A.. 1). 1-. RoOm on. J’. i”ricbard and U T’. Unit - 199.2. .Sril-umlOer

mreisgth and il,hlsratio,, alt is atlhcrrd (a winret cocci cops. S’oi.lTechnol 2189—190. cli: I.’ hi. 1016/ 0933-3630(92)90021-Ri5mon.nirsg, BFi, KID. l.hclr-r as/i’) .T0 oOO-08 Use of mnanssre, compsm. ad

SSSAj: Volume 75: Number 4 • July—Augrot 2011 1481

cosrrcrops to.mpplantcrop residue carbon in corn storer retnocedcroppingI 4

(‘;naroc 1DB .and “I’ CRam). 2102 lilt crt’; and linear cstroa,lrrrrrc20 3-225. /n J,H. lianc .crd Cat ‘Slipp. ccl,) Mahal.s olsoil analysis.. Pact4..SSSA.BrsokSa. 5. 555A, Madison, WI.

Ic.’, r 0 A. 3Llrocrs 333 Slitchell, L.S1. Liovck. 5.33 ..oor,’ P.C.Iic,mr.ar.d ‘ti t’iclro. 3ir0/. ionitratmn and clii& cca.ta mac ‘.rorrsatrtc’Oar cm.)..iafngra (slii.arncEs Saccantrona Cdicy I’rans. ASAF.45r.%IS-C2&

Kalrinths, PC.. 33. 50 Par iiananad D.C. Riror,. 2005. SPo clilrrsc.iI tctnpaannt.

rag. .sgfic. .‘Ls

Kaclcn, D.C. R. L.al., R..R Poiicrt, 3M. Kin.shlc, ilL. Hatfield, EM. MiranoacH.1. c r tclch A ide ‘af a a ar 1 3. par Hcia

Kaspai. ‘TIC.. [K. Radke, and ).. M. L.ailcn, 2001, ama‘I g.rain coscr crops a.ndwhen traffic riffcrs on infilerarion, conoit. and erosion, J. Soil Wirer

r,c,croac. .,ni) 5,,ot Ar, \Y.’..,i1r ‘A’ (S’il)ia.os, ca 33.5.

I 990. 53 after ci’a ‘cr..ps rofloenc on cr51100 ield. and ccl acedsoil properties. Cmnnaata, Soil Sri. Plane Anal. 25, 3O57- 3101)

101311 31)3/ 32° 3)93.59251)Kl:.,d’ to. Li, 1 SPa. Residue mars on r.al omorctia. ia. . c//1ar LW.

Coccc 1ed ) Liatsaging agrr,’oitocd raiders. Lcsels l5olal., ioca Raton, ELRosary, B., and T...E. Misrris 0. 21.102. Soil pcnetronicters and penetrability p,

363—55 5. P [51. l)arsraird. f/SC. Thpn led.) Mcthc.cls ocscol .asa(s 5s2aA maw a, ‘‘asp lcla,ir’arn. 1331SE (Cs Rnis, [1:1. Cc.ca. 33,5 .‘...rgr, also Ins acre.’ 0. 203)9. Crop rape

influences soil aggregation and orgrsnic matter under no”nllage. SoilVillage Res, 104r22. ‘-29. rkair 10.1.01 6/l,atill,200S. 11,0113

PA.. Cf Radciitk.,oida\ L 1 iaierocr. 1089 SVare. tals’iac coats.0 anii pcora.irnes .ltld nitrogen ffrtiiieer .ro’n i ernenr. Sal 5c a Soc. Ant. 153,1856—1862. doi. 10,21 36/sasai 1989,i’IPSIS99SOO5P0006004Ox

Meoes, 1.C., A.K. Ban.dick, 33.33. Dick’, and Pj. Bortomler. 1999. M’iacsb’ialh.rotnacs and ,tctis ate, .n’n 1 aggregates .tltrcted be ‘aintcr coat crops. coil5cr, S’s. Ant. ,1. 0.3’87.i—1i5i. dot 0.21 l6Ca5ai 1999 na-tXs

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1482SSSAJ: Volume 75: Number 4 - July—August 2011